UPDATE 1/6/04 – the Police Front Upper Strut Mount AD-931 is now obsolete, so the only choice you can make now is which bearing to use.
For replacement parts, Ford has two dimensionally different
front upper strut mounts and two dimensionally different front bearings, which
they specify in three different combinations.
Each of the front strut mounts come in standard rubber (black) and HD
(painted blue). For 89-90 (as
replacement parts – who knows what came from the factory), the SHO gets the HD
blue piece, as do the Police. The SLO,
of course, gets the standard rubber.
For 11/90-95 the part changed dimensionally, and the SHO is specified to
get the SLO piece, with only the Police getting the HD blue part. Since the blue (Police) and black
(SLO/SHO) parts in a given year are dimensionally the same, they are
interchangeable. The bearings also
changed dimensionally.
The parts are:
89-10/90 SLO (not SHO) Front Upper Strut Mount
AD-921-A/E6DZ-18183-AA
89-10/90 SHO/Police Front Upper Strut Mount
AD-923-A/E7DZ-18183-AA (obsolete)
11/90-95 SHO/SLO Front Upper Strut Mount
AD-930-A/F1DZ-18183-AA
11/90-95 Police Front Upper Strut Mount
AD-931-A/F1DZ-18183-BA (obsolete)
89-11/90 and 94-95 Front Strut Bearing F4DZ-3B455-A
11/90-93 Front Strut Bearing F1DZ-3B455-A
As you can see, the first bearing is used with the two front
mounts. More on that below
Here are the dimensions of the mounts for top of mount (i.e.
underside of strut tower) to bearing mounting surface:
89-90 mount 0.49"
11/90-95 mount 0.88"
As we can see, the newer mount places the bearing mounting
surface further down WRT to the top of the strut tower. The height of the centre portion that mounts
the strut shaft does not change between the two, however ...
For the bearings, it's difficult to measure the bearing
surface to spring mounting surface, but the F4DZ part has the spring mounting
surface 0.15" below the bearing mounting surface in the mount, while the
F1DZ part has the spring mounting surface 0.18" ABOVE the bearing mounting
surface, i.e. the F1DZ bearing has a very deep cup.
When you put these together for the different years as
specified, you get the following top-of-mount (i.e. bottom of strut tower) to
top of spring distances: (remember that
in all cases, the strut shaft mounting hole vertical placement remains the same
in either mount...)
89-90 Front Upper Strut Mount (obsolete)
89-11/90 and 94-95 Front Strut Bearing
0.64" top of mount to top of spring
11/90-95 Police (obsolete) or SHO/SLO Front Upper Strut
Mount
11/90-93 Front Strut Bearing
0.70" top of mount to top of spring
11/90-95 Police (obsolete) or SHO/SLO Front Upper Strut
Mount
89-11/90 and 94-95 Front Strut Bearing
1.03" top of mount to top of spring
There are at least three points to gather from this info:
1. The rubber ring
on the outside of the bearing part that sometimes makes contact with the strut
tower, and thus noises (for which the spacer recall is to correct) is quite a
bit higher in the first two examples, whereas in the 3rd, it is quite far
down. Thus the last combination should
never need the spacers to correct noise.
2. The latter combo
raises the front of the car by about 0.35" compared to the first two.
3. The latter combo, by maintaining the same strut shaft mounting height, while having the top of the spring down further, actually increases available strut compression travel by the same 0.35" (with a corresponding decrease in extension). Note that while a spacer (which mounts on TOP of the strut mount) raises the car by about 0.25" and moves the top of the bearing 0.25" away from the strut tower, it does NOT increase available compression travel, since the strut shaft mounting location in the mount is also lowered. Note that 'lowered' and 'raised' all depend on your point of reference ... :-)
Based on the above, I would always recommend the 11/90-95
Front Upper Strut Mount for all cars
because the equivalent Police 89-90 piece is obsolete, and the 89-90 SLO
piece would only work with the 89-11/90 and 94-95 Front Strut Bearing, and that
combination is nearly guaranteed to rub and make noises.
If available strut compression travel (i.e. resistance to
bottoming out) and lack of rubbing noise is more important than lowering the
front of car by a paltry 0.35”, then I recommend the 89-11/90 and 94-95 Front
Strut Bearing for all cars. Since this
would be the most important to me, I would recommend the 89-11/90 and 94-95
Front Strut Bearing for all cars, period.
If lowering the front of the car is more important than eliminating the strut noise and increasing available strut compression travel, then I recommend the 11/90-93 Front Strut Bearing for all cars, but bear in mind that you may have to add spacers to eliminate rubbing noises, and then you increase the ride height without any corresponding increase in compression travel.